1. Field of the Invention
The present invention relates to a multiple disc clutch apparatus which is capable of securely preventing adhesion between metallic plates serving as driven plates (SP) and drive plates (FP) when frictional members are lost.
2. Related Background Art
FIG. 5 is a schematic cross-sectional view of a multiple disc clutch apparatus according to a prior art. In this multiple disc clutch apparatus, several number of driven plates 1 (SP) and drive plates 2 (FP) are arranged alternately to overlap with each other. The driven plate 1 is a metallic plate having a spline on its outer periphery, while the drive plate 2 is a metallic plate having a spline on its inner periphery and facing members 3 (frictional members or linings) are attached onto both faces thereof. The multiple disc clutch is arranged to be engaged or released in an action mode or a non-action mode switched over by the pressing force of a piston 4. A reference numeral 5 denotes a clutch drum; 6 a retainer plate; 7 a canceller; and 8 a return spring, respectively.
Incidentally, when the frictional members of the multiple disc clutch are lost, it is feared that the metallic plates serving as the driven plates (SP) and the drive plates (FP) might be caused to adhere to each other.
In the conventional apparatus disclosed in Japanese Patent Application Laid-Open No. 3-9119, the thickness of the spline portion is set as larger than that of another portion. With this arrangement, the surface pressure acting on the spline portion is decreased, so as to prevent generation of friction.
However, in Japanese Patent Application Laid-Open No. 3-9119, since the spline portion of the driven plate is bent, the height of the spline portion is small, so that the spline portion is required to have a certain thickness in order to maintain heatmass, which may resultantly increase the cost since a bending process is required.